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Old 06-18-2015, 12:13 PM   #1
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Problems with /home mount on a btrfs subvolume - systemd

Hello Guys;

I have been trying for the last day or so to get this working on my gentoo system.

I am currently using systemd as the runtime init system. My system has an encrypted root and home partitions that are sitting on a btrfs file system as subvolumes. In order to get this working I had to create a custom initramfs image. I attempted to use dracut but it simply hangs at boot and never prompts for the password.

The system will with my current initram mount root just fine however when I try and set my /home as auto mount systemd will try and start the dev-map-rootpool.device and fail. It fails because cryptsetup has already created the correct devices in /dev/mapper for the btrfs file system. Because / and /home are on the same physical device /dev/mapper/rootpool, and my initram does not include systemd the device is seen as down.

So my question is if there is a way to setup my init in my intramfs to pass on notification to systemd that the device is up? I have tried to move /dev and /proc and even /sys to the running system from the startup environment but to no avail.

I am also unable to just mount /home in the initram as when systemd starts it will see that home.device is attached to a down device and then unmount it.... This also goes for trying to make a custom .start file in /etc/local.d.

I would rather not try and embed systemd into my initramfs as doing so I am sure is painful in the small startup environment but I fear this is the only option. I have looked around online extensively and cant find good info on how to accomplish this the only info I can find is from freedesktop which simply states to imbed systemd into your initram.
Old 06-19-2015, 11:19 AM   #2
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I have actually solved this problem. I used dracut to make me a initramfs image and then decompressed the archive into a dir. I then checked for all the files it would need in the image and noticed that it was failing to include my crypttab file. I then manually added the file back in recreated the image using my own script.

Now I am prompted for my password on boot and everything works as intended.

I am still curious however if there is a way to inform systemd in some way that /dev/mapper devices are actually available when they are booted with a custom initramfs. I don't relish the idea of having a complicated initramfs that requires systemd to be imbeded.


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